Note: "permalinks" may not be as permanent as we would like,
direct links of old sources may well be a few messages off.
Federico, out of curiosity: does this throughput drop also occur when you activate your "TestGroup00" VG in exclusive mode? Cheers, Florian On 2009-06-26 12:14, Federico Simoncelli wrote: > Hi all I was testing the performances of CLVM over DRBD and I found > that the write speed on a logical volume is quite slow (15.1 MB/s) > compared to the write speed on the raw drbd0 device (47.2 MB/s). > Is this a known issue or there might be something wrong in my configuration? > > I'm using a Smart Array E200 (128Mb BBWC with cache enabled) which > normally writes at ~50MB/s. > I've a plain drbd.conf configuration (the parameters: al-extents, > sndbuf-size, max-buffers, max-epoch-size, unplug-watermark, > no-disk-barrier, no-disk-flushes, no-md-flushes are set to the default > values). > The connection between the nodes is done with two BCM5722 Gigabit > Ethernet (tg3) with default mtu (1500). > > I think my setup shouldn't be the problem since writing on the drbd > device is performing quite well (47.2 MB/s). > > Test: > > # sync && dd if=/dev/zero of=/dev/drbd0 bs=1M count=100 oflag=direct > 100+0 records in > 100+0 records out > 104857600 bytes (105 MB) copied, 2.22116 seconds, 47.2 MB/s > # pvcreate /dev/drbd0 > Physical volume "/dev/drbd0" successfully created > # vgcreate -cy TestGroup00 /dev/drbd0 > Clustered volume group "TestGroup00" successfully created > # vgs > VG #PV #LV #SN Attr VSize VFree > TestGroup00 1 0 0 wz--nc 465.71G 465.71G > VolGroup00 1 2 0 wz--n- 148.94G 0 > # lvcreate -n SpeedTest00 -L 4G TestGroup00 > Logical volume "SpeedTest00" created > # sync && dd if=/dev/zero of=/dev/TestGroup00/SpeedTest00 bs=1M > count=100 oflag=direct > 100+0 records in > 100+0 records out > 104857600 bytes (105 MB) copied, 6.96609 seconds, 15.1 MB/s > -------------- next part -------------- A non-text attachment was scrubbed... Name: signature.asc Type: application/pgp-signature Size: 260 bytes Desc: OpenPGP digital signature URL: <http://lists.linbit.com/pipermail/drbd-user/attachments/20090702/b9f58c21/attachment.pgp>